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Sedna Simulation
This is a simulation of what one would expect to find on a terraformed Sedna, using formulas from Math And Terraforming. Please note that not even the supercomputers at NASA can provide us with a perfect simulation. The information showed here is only an approximation. Basic data Before everything, please note that there are many unknown parameters about Sedna. Because of this, the simulation will be less accurate then in case of other celestial bodies. *Distance from Sun: **Aphelion: 960 AU or 144000 million km **Semi-major axis: 506.8 AU or 75800 million km **Perihelion: 76.092 AU or 11400 million km *Diameter: 1000 km (estimated) *Solar Constant: **Aphelion: 0.00000000721 **Semi-major axis: 0.0000000260 **Perihelion: 0.00000150 *Mass: ??? Earths *Mean density: ??? kg/l *Year length: 11400 Earth years *Day length: 11.3 hours *Rotation axial tilt: ??? degrees Important! The solar constant of 0.002 is the lowest that can support plant life. Because of this, no celestial body beyond Neptune could be terraformed without an artificial source of light. Surface Composition & Internal Structure We cannot make any simulation if we don't know what Sedna is made of. Unfortunately, this is just the case. We know its diameter to be roughly 1000 km (with an error of 10%, which is large enough), we know its day length and we know its orbit. Spectroscopic data revealed on the surface presence of frozen gasses. One model suggest that its surface is made of: *24% Triton-type tholins *7% amorphous carbon *10% nitrogen ices *26% methanol *33% methane *Water ice on surface: <1%. About the interior, nothing is known. About the origin of Sedna, there are many speculations: It could be coming from the Oort Cloud, it could be scattered from the Kuiper Belt or it could be captured by the Sun from another solar system. Other possibilities is that it could be ejected from the inner Solar System, later coated with frozen gasses from the place where Sedna now orbits. The discovery of Sedna let scientists suspect the existence of planet nine, a super Earth located in the far reaches of the Solar System. Its origin might help us suspect what its internal composition might be. Sedna could had interacted with planet nine at some point. Surprisingly is the fact that Sedna has no detectable moons. At its distance to the Sun, Sedna has a large sphere of influence, so it can easily host moons. The lack of any moon might suggest that at some point Sedna went very close to another celestial body who disrupted its orbit. The fact that we see no ice on its surface could suggest that Sedna had no recent cryovolcanic activity. Also, it can suggest that no large crater impact occurred in the recent past, to expose its icy crust... or it can suggest that Sedna has no ice crust, which makes things very complicated. Methane on the surface appears to be very old and not crystalized. This suggest that Sedna never went close enough to the Sun in recent time and never had an atmosphere. Interior Structure As for now, we don't know its mass. Sedna could be entirely made of frozen gasses, it could be made of water ice, it could be a mixture of ices and rocks or it could be made of rock, coated with solidified gasses on the surface. Sedna could be differentiated into a rocky core and an icy mantle or could be undifferentiated. What is known with a very high probability, is that Sedna is not active. Because of that, we can speculate that its core is cold and it has no subsurface ocean. So, Sedna gives us a lot of possibilities. Its density can vary from low values like 0.5 kg/l (like Hyperion to high values of 5 kg/l, like rocky planets. Each case comes with completely different internal structures and terraforming models. The following is a table showing possible scenarios. Mass (Earth = 1) Gravity (Earth = 1) Density (Earth = 1) 0.00003 0.00488 0.342 0.0000399 0.00649 0.455 0.0000530 0.00863 0.606 0.0000706 0.0115 0.806 0.0000939 0.0153 1.072 0.000125 0.0203 1.425 0.000166 0.0270 1.896 0.000221 0.0359 2.521 0.000294 0.0478 3.353 0.000391 0.0636 4.460 0.000520 0.0845 5.931 With these values, we have everything included, from a planet made of frozen gasses to one made of iron and coated with ices. Temperature Main article: Temperature. Before everything, we must acknowledge that Sedna has a very elliptical orbit. Because of this, with the same amount of greenhouse gasses, it will be very hot in summer and very cold in winter. For humans, the best temperature appears to be +15 C. We will see if, with the use of greenhouse gasses, this is possible to maintain. See Temperature for more details regarding formulas used for this simulation. Void temperature is the temperature a celestial body, neutral grey in color, exposed to a source of light of a known Solar Constant (Ks). For Sedna, we have the following values: Aphelion: Ks = 0.00000000721, Semi-major axis: ks = 0.0000000260, Perihelion: 0.00000150. *Aphelion: Ks = 0.00000000721, void temperature = -270.31 C or 2.84 K. *Semi-major axis: Ks = 0.0000000260, void temperature = -269.24 C or 3.91 K. *Perihelion: Ks = 0.00000150, void temperature = -262.38 C or 10.77 K. By amplifying temperatures (adding greenhouse effects), we get the following values: For 15 C at aphelion: *Semi-major axis: 124 C *Perihelion: 1093 C For 15 C at semi major axis: *Aphelion: -64 C *Perihelion: 521 C For 15 C at perihelion: *Aphelion: -197 C *Semi major axis: -169 C. As one can see, if we use only heat and light from the Sun, Sedna will experience very hot summers and very cold winters, unless some technology will add or remove greenhouse gasses from time to time. There is no way to get a concentration of greenhouse gasses that will allow life to resist all along the orbital path of Sedna. And since the planet will require over 11000 Earth years to complete one orbit around the Sun, seasons will last centuries or millennia. For this, Sedna will need Greenhouse Gases. The Greenhouse Calculator shows us that we will need huge amounts of sulfur hexafluoride to keep the correct temperature. But will greenhouse gasses be enough? Or, the solar constant is far too small for this? Let's do the math. Also, let's compare the values with an Earth-like atmosphere: *At aphelion: **1990000 kg sulfur hexafluoride per square m **199 times an Earth-like atmosphere *At semi-major axis: **552000 kg sulfur hexafluoride per square m ***55 times an Earth-like atmosphere At perihelion: **9570 kg sulfur hexafluoride per square m **98% of an Earth-like atmosphere. It is true that an Atmosphere around small bodies will be fluffy, reaching even 1000 km wide, containing far more gas per square km then Earth's, but even so, it will not be enough to keep so much greenhouse gas. This also comes with a problem. We might have enough sulfur on Sedna, but the amount of needed fluoride is far beyond what we can get. In addition to this, we must acknowledge the atmosphere cooling effect that occurs when above the greenhouse insulation it is very cold. Exposed to cosmic coldness, gasses will freeze and fall back, cooling the lower layers of the atmosphere. As a direct result, surface temperature will drop. Even greenhouse gasses, if the atmosphere is made only of them, will cool and freeze. Sedna receives only little light from the Sun. Therefore, it heats very slow: *At aphelion: 1 degree C in 24200 Earth years *At semi-major axis: 1 degree C in 9700 Earth years *At perihelion: 1 degree C in 116 Earth years. Atmosphere cooling effects will occur much faster. One can clearly estimate that atmosphere cooling effects will occur much more often. However, plants will not survive on Sedna with the dim light they receive from the Sun. They need an alternative source of light. The only possibility is to use an Artificial sun. There are a few different approaches to this subject (we will discuss about them in the next sections). Because we know nothing clear about Sedna (including its mass and gravity), we can only speculate. The only solution is to conduct multiple simulations, to see if and how can an atmosphere have stability, at different solar constants and at different mass and gravity estimations. Atmosphere See Atmosphere Parameters Is Sedna able to support an atmosphere? Unfortunately, we don't know its mass, but we know its diameter. The simulation will be very complex, using various models for Sedna's composition. First of all, we want to see at what temperature oxygen molecules share a similar stability with the atmosphere of the Moon (see Luna Simulation). Atmosphere stability for oxygen molecules (stability like in Moon's terraformed atmosphere): Mass (Earth = 1) Density (Earth = 1) Temperature (degrees C) 0.00003 0.342 -229 0.0000399 0.455 -220 0.0000530 0.606 -210 0.0000706 0.806 -200 0.0000939 1.072 -190 0.000125 1.425 -180 0.000166 1.896 -165 0.000221 2.521 -150 0.000294 3.353 -130 0.000391 4.460 -110 0.000520 5.931 -80 Next, let's see what is the minimum temperature at which water molecules will not move faster then the escape velocity (a metastable atmosphere). Atmosphere stability for water molecules (metastable): Mass (Earth = 1) Density (Earth = 1) Temperature (degrees C) 0.00003 0.342 -200 0.0000399 0.455 -190 0.0000530 0.606 -175 0.0000706 0.806 -160 0.0000939 1.072 -140 0.000125 1.425 -120 0.000166 1.896 -100 0.000221 2.521 -70 0.000294 3.353 -40 0.000391 4.460 -10 0.000520 5.931 +30 This calculation does not include solar wind erosion. Conclusion: Surprisingly, Sedna is able to host an atmosphere. Even at a very low density (a scenario in which Sedna will be completely made of frozen gasses), the little planet is able to hold something. However, if Sedna is made of rock, or has a similar composition with Pluto (rock and ice), its atmosphere will be stable in conditions similar to those encountered around Jupiter's orbit. The following, is a simulation for its atmosphere. If the atmosphere will get too fluffy, it will escape into space. For this simulation, we want the atmosphere not to extend beyond one planetary radius (500 km high). From that height on, it is unstable. Simulation for atmospheric height = 500 km, pressure at sea level = 1 bar: Mass (Earth = 1) Density (Earth = 1) Temperature (degrees C) 0.00003 0.342 -270 0.0000399 0.455 -266 0.0000530 0.606 -260 0.0000706 0.806 -262 0.0000939 1.072 -259 0.000125 1.425 -253 0.000166 1.896 -243 0.000221 2.521 -234 0.000294 3.353 -227 0.000391 4.460 -213 0.000520 5.931 -196 As one can see, in order to maintain a stable atmosphere around Sedna, not too fluffy to escape into cosmos, we need to keep it a low temperature. Of course, on ground, we want to have +15 C, because this is the optimal temperature for humans to live. A layer of greenhouse gasses will ensure this. Basically, we will have two layers in the atmosphere: one below and one above the greenhouse gas buffer. The lower layer will be hotter and the upper layer colder. Because molecules move faster at higher temperatures, the lower layer will push the upper one further up. Overall, Sedna's atmosphere will rise higher then its radius, but not higher then its diameter. Artificial sun Main article: Artificial sun. Because plants cannot survive with the low luminosity available at Sedna's orbit, it will be impossible to maintain life without an extra source of light. There are several ways to do this. Orbital Stations. It is possible to build an orbital station and build on it a huge nuclear generator, that will produce light and heat, sending it towards Sedna. We can also build several smaller stations, encircling Sedna on various orbits, equatorial, tilted and even polar. The major problem is that Sedna will have a fluffy atmosphere that will also trap a lot of moisture, that will reflect a significant part of the light and heat (infrared light). We want only to heat the planet, not its upper atmosphere, which must cool down and decrease its size as much as possible. Atmospheric Balloons. For this, we need many balloons, each one carrying one nuclear generator. The main disadvantage is that balloons will move. So, in some places their numbers will be higher and in others, lower. The direct result is that there will be hotter and colder places. This can create an instability and can produce holes in the greenhouse layer, creating storms and cooling the planet in a runaway effect. The balloons can be destroyed by the powerful winds created. Surface Stations. Surface power plants can produce light and heat. However, the energy needs to be radiated towards the surface and not towards the cosmos. In order to do this, they need to have powerful reflectors pointing to nearby areas. Also, above a station there could be a large balloon coated with reflective material, that will reflect light and heat to the surface. The principle is simple, but it requires a large number of stations. Sedna is smaller then Earth. Its curvature will force us to build more power plants then would be required for an Earth - like planet. Suppose there will be 10 km between power plants, we will need one for each 100 square km and 31500 power plants for the whole surface of Sedna. However, if we want to avoid wasting energy, for better effects, we will need one power plant at each square km. That will require 3.15 million power plants. The main advantage of this technology is that it delivers heat directly in the lower layers of the atmosphere, allowing the higher layers to cool down. In the following, we will try to maintain a habitable Sedna with the use of surface stations. Energy required. On Earth, the Solar Constant is roughly 1.98 calories per minute. It can also be described as 1.361 kW/square meter or 1.361 GW/square km. As shown above, we don't know the mass of Sedna and its composition. Because this, during this simulation, we made a lot of estimations. The following table contains values. The table depicts: *Solar Constant Ks - the energy output from the surface stations *Void Temperature Vt - the temperature expected for the solar constant without greenhouse gasses *Energy output Ew - GW/square km *Total energy output Gl - for the whole surface of Sedna. Solar constant Void temperature Energy output Total energy Times Earth's Energy Ks units degrees C GW/square km total Gw 7098 GW/s 0.002 -201 0.0013 4157 0.586 0.003 -194 0.0020 6236 0.879 0.0045 -186 0.0030 9353 1.318 0.00675 -178 0.0045 14030 1.977 0.0101 -167 0.0067 21050 2.97 0.0152 -157 0.010 31570 4.45 0.0228 -145 0.012 47350 6.57 0.0342 -133 0.022 71030 10.01 0.0513 -120 0.034 106500 15.01 0.0769 -103 0.051 159800 22.5 0.115 -86 0.076 239700 33.8 0.173 -68 0.11 359600 50.7 0.259 -47 0.17 539600 76.0 0.389 -24 0.26 809000 114.0 0.584 1 0.39 1214000 171.0 0.858 28 0.58 1820000 256 1.31 58 0.87 2731000 385 1.98 92 1.30 4096000 577 Because there are many unknown factors about Sedna, it is impossible to come with a specified value. The minimum energy output is for a solar constant Ks = 0.002, which is the lowest value that allows plants to survive. The maximum value is limited by the atmosphere parameters. Because the mass of Sedna is unknown, we can only estimate, for various scenarios, which is the maximum value for Ks. Climate Simulation Main article: Climate. The climate of a terraformed Sedna will not be influenced by the Sun. Instead, it will be controlled by the greenhouse effect and by the energy output from the surface power plants. Again, because we don't know much about Sedna, we will use a broad set of values. Depending on greenhouse effect, power plants will have to produce a certain amount of light and heat to maintain a surface temperature of 15 degrees C. Sedna will not experience a climate dependent on latitude, on axial tilt or on day-night fluctuations. The Sun will have no influence, since the solar constant will be less then 1% of the artificial constant (energy output from power plants). In the following tables, we will conduct two simulations: Temperature variation between poles, assuming that energy will be produced only at one pole: Solar constant Temperature difference Ks units between poles (degrees C) 0.002 0.57 0.003 0.63 0.0045 0.69 0.00675 0.76 0.0101 0.83 0.0152 0.91 0.0228 1.00 0.0342 1.08 0.0513 1.17 0.0769 1.21 0.115 1.36 0.173 1.43 0.259 1.48 0.389 1.50 0.584 1.57 0.858 1.60 1.31 1.87 1.98 2.11 Atmosphere heating speed (24 hours): Solar constant Heating in 24 h Ks units (degrees C) 0.002 0.0079 0.003 0.0119 0.0045 0.0178 0.00675 0.027 0.0101 0.040 0.0152 0.060 0.0228 0.090 0.0342 0.135 0.0513 0.21 0.0769 0.30 0.115 0.45 0.173 0.68 0.259 1.02 0.389 1.54 0.584 2.3 0.858 3.4 1.31 5.2 1.98 7.8 One can see that Sedna will have a special type of climate named Monoclime. There will be little temperature differences between hemispheres. In such conditions, the atmosphere tends to be saturated with moisture up to 100%. Excess water accumulates in the atmosphere, creating clouds and hazes, but with little rain, because there are no significant temperature oscillations. Complete Climate Control: Unlike any Outer Planet, which has its climate dominated by its Sun, Sedna will be controlled by humans completely. We can gradually heat Sedna by turning all power plants to maximum, gradually increasing temperature to 20, 25 or even 30 degrees C. Then, we can make them work at very low capacity, decreasing temperature to 10, 5 or even 0 degrees C. This way, Sedna will be experiencing winters and summers. Heating episodes will force the atmosphere to absorb moisture. During that period of time, the sky will be blue clear. Then, during cooling episodes, the atmosphere will lose heat. It will be raining all over the planet as temperature will drop. Atmosphere Cooling Effect: Any outer planet who orbits too far from its sun, will experience atmospheric cooling effects. The outer layers of gas in the atmosphere will be exposed to the coldness of space, cooling. As this happens, gasses freeze and fall down, cooling the layers of gas they encounter. Because at Sedna we will use ground stations and not an artificial sun, most of light and heat will be dispersed on the surface, without interacting with the upper atmosphere. So, cooling events will occur. Conclusion: Sedna will have a unique climate pattern, where humans will have entire control. Temperature can be lowered or increased at any moment with the help of the large set of energy power plants on the surface. Geography See also: Geography. The main problem is that not even the most powerful telescopes could detect any surface features on Sedna. So, we really don't know how it looks like. There is a high chance that Sedna is round, but it still could have an irregular shape. There are 5 major concepts to transform an icy Outer Planet: #Increase the heat, melt the ice and transform it into an Oceanic Planet, then leave it as it is. #If possible, build Artificial Continents after melting all the ice. #Use Ground Insulation, to save the icy crust, then cover it with solid rock. #Heat the moon, until solid particles from the molten ice will form a natural insulation above the ice crust (see Iapetus Simulation). #Create an Ocean Insulation layer, that will allow us to build an ocean without transforming the atmosphere. Depending on what we will find on Sedna, some methods can be possible, some not: *If Sedna is made of frozen gasses, then it has a too low mass and will be unable to hold an atmosphere (see above). *If Sedna is made of water ice and frozen gasses, still too small to sustain an atmosphere, ocean insulation remains an option. *If Sedna is only made of water ice, with tenuous amounts of rocks and frozen gasses, method 4 is the most feasible. *If Sedna is made of water ice and rocks and has an irregular shape, methods 1 and 2 are possible. We need to melt the ice to gain a more circular form. *If Sedna is made of water ice and rocks and has a circular shape, then method 3 is the best option. Ground insulation will allow us to save energy for melting the ice. *If Sedna has a large rocky core, coated with ice and frozen gasses, then melting the ice will form oceans and continents. Conclusion: Until a spaceship visits Sedna, we have no way to know surface details. So, it is impossible to talk now about Geographic features. The Sky At aphelion, the Sun will be as luminous as the Moon on Earth when it is half illuminated. At perihelion, the Sun will bring enough light so that you can see where you're walking. However, the ground energy power plants will bring far more light. You will be able to see the Sun in the sky anytime when the atmosphere is clean. No planets will be visible from Eris at all (see Magnitude and Angular Size for details). As for now, we don't know about the presence of any moon orbiting Sedna, so we don't know if a moon will be visible. Very interesting will be to see Sedna from space. The little planet will be like glowing, producing its own light. On orbiting moons (if they exist) and Space Stations, it could be possible to see where you're going with this light. Human Colonies Main article: Population Limit. Depending on the amount of energy produced by the power plants, Sedna's ecosystem can tolerate the following population: Solar constant Population limit Largest city Agriculture productivity Ks units people population people/square km 0.002 31 000 124 0.30 0.003 47 000 186 0.45 0.0045 70 000 280 0.68 0.00675 105 000 420 1.02 0.0101 157 000 630 1.53 0.0152 240 000 940 2.3 0.0228 350 000 1 410 3.5 0.0342 530 000 2 100 5.2 0.0513 800 000 3 200 7.8 0.0769 1 190 000 4 800 11.6 0.115 1 790 000 7 200 17.5 0.173 2 700 000 10 700 26 0.259 4 000 000 16 100 39 0.389 6 000 000 24 000 59 0.584 9 100 000 36 000 88 0.858 13 600 000 54 000 133 1.31 20 000 000 82 000 199 1.98 31 000 000 122 000 300 However, because we use ground power plants to heat the planet, we can easily adapt for an equilibrium. Suppose that human activities produce too much heat in an area (a too large city or too many industrial companies on a small surface). To compensate, we can degrease energy output of a ground energy plant. Because of this, the entire population can live in a single large city. The problem remains agriculture capacity, because plants need a certain amount of light to produce food. Sedna will be highly dependent on its artificial sources of light and heat. This will create some financial problems (see Maintaining a terrafomed world). There will be many costs that settlers will have to support: *fuel the ground power plants *Maintain the ground power plants *Maintain the ground insulation (if it exists) *Replenish atmosphere losses. Industry This subject is very important, because revenues from the economy must pay for operating the ground power plants. The economy must be very powerful and that will require a powerful industry. Because of the high distance to the inner Solar System (mainly at aphelion), Trade Routes to and from Sedna will be expensive. Cargo and passengers will need long waiting times or high fuel consumption. There is also a chance that Sedna will be an enclosed world, producing all what it needs, but doing very little commerce to the outside world. another possibility is that industrial corporations, willing to extract and refine organic compounds that naturally exist on Sedna, will be against terraforming and will suggest Industrial colonization instead. Agriculture Main article: Plants on new worlds. Plants cannot survive with a solar constant below 0.002. Without an artificial source of light, Agriculture outside illuminated domes is impossible. Transportation Because we know nothing about Sedna's surface, it is impossible to know if and how a ground transportation network will look like. What is for sure is that air transport will be possible, given the low gravity. Also, on the surface, vehicles will tend to lose contact with the ground, because of low gravity. Tourism Triton and Pluto (see Triton Simulation and Pluto Simulation) will be considered places at the end of the world, since they are the furthest places where terraforming can be done only using light and heat from the Sun. Eris (see Eris Simulation) and Sedna are something different. As shown above, plants cannot survive on Eris or Sedna without an extra source of light. And even if on the sky of Eris the Sun will still be relatively bright, on the sky of Sedna, it will only be a star. Eris and Sedna will be the first celestial bodies located beyond the end, beyond the outer limit where life is possible only using power from the Sun. This will be a fascinating place to visit. Many tourists will come to see with their own eyes the technological wonder that made Sedna from a dead world a new paradise for humans. Wild Life With the use of surface power plants, Sedna can offer a multitude of climate patterns. Overall, the little planet will experience the same type of climate on its entire surface. The fact that it is possible to create a summer or a winter, will make Sedna the only place in the Solar System to have seasons like those found on Earth. Sedna will be able to host many organisms from Earth. Conclusion Because Sedna is too far away, it was impossible to conduct a single simulation. One can find here many variants of climate, atmosphere, temperature, population density and luminosity. The real Sedna will fit only a single model. As one can see, there are huge variations between models and in some cases (for example a planet with too low mass), terraforming is impossible. Only the day when a spaceship will visit Sedna, we will know what really lies there. The lessons humans will learn while terraforming and living on Sedna are very important, because principles and technologies used here can as well be used on a Rogue planet. The only major advantage that Sedna has is its proximity to Earth, compared to planets that are free-floating in interstellar space. Sedna, with so many unknown parameters and so many unknown outcomes, is the most difficult celestial body to simulate in the Solar System. Unlike other planets and moons, which required one, two or at maximum three simulations, Sedna required over 10, using different parameters complex formulas.